Superheat Sensor

ABSTRACT

A superheat sensor includes a housing, a pressure sensor mounted within the housing, a temperature sensor that is integrated to the pressure sensor, and/or is external to the pressure sensor, a fluid passageway connecting the pressure sensor to a source of superheat fluid, and a processor.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.61/611,747 filed Mar. 16, 2012.

BACKGROUND

Various embodiments of a fluid sensor are described herein. Inparticular, the embodiments described herein relate to an improvedsuperheat sensor.

There are many fluid system applications that require knowledge of afluid's superheat in order to optimize the state of the fluid system.These systems include, but are not limited to, HVAC systems. Fluids thatmay be used within these systems include, but are not limited to,refrigerants.

As used herein, the term superheat is defined as the condition where thefluid, regardless of the system type, has excess energy relative to thefluid's boiling point. This excess energy may be measured as the numberof degrees of temperature above the fluid's boiling point, or superheat.

Methods of measuring superheat are known. For example, U.S. Pat. No.5,070,706 discloses a superheat sensor having a single coupling to afluid channel carrying fluid through which superheat is being measured.

U.S. Pat. No. 5,820,262 discloses a refrigerant sensor for calculating asuperheat value for refrigerant material. The sensor has an internalpressure sensor and an internal temperature sensor.

U.S. Patent Publication No. 2011/0192224 discloses a superheat sensorhaving a flexible wall that defines an interface between an inner cavityhaving a charge fluid therein and the flow channel in thermal contactwith the fluid flowing therein. The flexible wall is adapted to conductheat between the flow channel and the inner cavity.

U.S. Patent Publication No. 2011/0222576 discloses method forcalibrating a superheat sensor.

Typical superheat sensors do not provide automatic fluid-type detection,high sensitivity, and resolution under a wide range of pressures, storesuperheat and related parametric history, generate alarms, and provide avariety of industry standard reporting options.

Accordingly, there remains a need in the art for an improved sensor andmethod of identifying and measuring superheat in fluids; especiallyrefrigerants in HVAC systems.

SUMMARY OF THE INVENTION

The present application describes various embodiments of a superheatsensor. One embodiment of the superheat sensor includes a housing, apressure sensor mounted within the housing, a fluid passagewayconnecting the pressure sensor to a source of superheat fluid, and aprocessor.

In a second embodiment, a method of sensing superheat includesconnecting a fluid inlet member of a superheat sensor to one of aplurality of fluid systems and allowing fluid to flow from the fluidsystem to which the superheat sensor is connected to the superheatsensor. A temperature of the fluid in the fluid system is sensed withone of an internal temperature sensor mounted within a housing of thesuperheat sensor and an external temperature sensor mounted outside ofthe housing of the superheat sensor. A superheat of the fluid in thefluid system is then calculated.

In a third embodiment, a method of sensing superheat includescalibrating a superheat sensor and connecting a fluid inlet member ofthe superheat sensor to one of a plurality of fluid systems. Fluid isallowed to flow from the fluid system to which the superheat sensor. Atemperature of the fluid in the fluid system is sensed and a fluid typeof the fluid in the fluid system is detected. A superheat of the fluidin the fluid system is then calculated and error conditions aredetermined. Superheat and related parametric and alarm data are stored.The superheat sensor is disconnected and subsequently connected toanother of the plurality of fluid systems without re-calibrating thesuperheat sensor.

Other advantages of the superheat sensor will become apparent to thoseskilled in the art from the following detailed description, when read inview of the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a first embodiment of the universalsuperheat sensor according to the invention.

FIG. 2 is a cross sectional view of the universal superheat sensorillustrated in FIG. 1.

FIG. 3 side elevational view of a second embodiment of the universalsuperheat sensor.

FIG. 4 is a cross sectional view of a third embodiment of the universalsuperheat sensor.

FIG. 5 is an exploded perspective view of a fourth embodiment of theuniversal superheat sensor.

DETAILED DESCRIPTION

The present invention will now be described with occasional reference tothe specific embodiments of the invention. This invention may, however,be embodied in different forms and should not be construed as limited tothe embodiments set forth herein. Rather, these embodiments are providedso that this disclosure will be thorough and complete, and will fullyconvey the scope of the invention to those skilled in the art.

Unless otherwise defined, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this invention belongs. The terminology used in thedescription of the invention herein is for describing particularembodiments only and is not intended to be limiting of the invention. Asused in the description of the invention and the appended claims, thesingular forms “a,” “an,” and “the” are intended to include the pluralforms as well, unless the context clearly indicates otherwise.

Unless otherwise indicated, all numbers expressing quantities ofingredients, properties such as molecular weight, reaction conditions,and so forth as used in the specification and claims are to beunderstood as being modified in all instances by the term “about.”Accordingly, unless otherwise indicated, the numerical properties setforth in the specification and claims are approximations that may varydepending on the desired properties sought to be obtained in embodimentsof the present invention. Notwithstanding that the numerical ranges andparameters setting forth the broad scope of the invention areapproximations, the numerical values set forth in the specific examplesare reported as precisely as possible. Any numerical values, however,inherently contain certain errors necessarily resulting from error foundin their respective measurements.

As used in the description of the invention and the appended claims, thephrase “universal superheat sensor” is defined as a superheat sensorwhich contains all the necessary sensors, electronics, and intelligenceto automatically detect multiple fluid types, such as refrigerants,without re-calibration, and report the superheat of the multiple commonfluid types used in residential, industrial, and scientificapplications.

The superheat sensor according to the invention is a single,self-contained, stand-alone device which contains all the necessarysensors, electronics, and intelligence to automatically detect the fluidtype, such as refrigerant, and report the superheat of multiple commonfluid types used in residential, industrial, and scientificapplications. The superheat sensor according to the inventioncommunicates this information in a cost effective way using industrystandard reports. It stores this information in a local memory devicefor subsequent retrieval of historical data. Additional data storage maybe provided, such as through removable memory cards, and via anoff-board computer, such as a laptop computer. The superheat sensoraccording to the invention may also be configured to provide the uservarious alarms for conditions such as low pressure (fluid leakage), lowand/or high superheat (indicators of system flooding and out-of-rangesystem efficiency), excessive pressure (system overcharge or imminenthardware failure), temperature out of range, and like conditions.

Referring now to FIGS. 1 and 2, a first embodiment of the universalsuperheat sensor 10 includes a housing 12, a fluid inlet member 14, anintegrated pressure and temperature sensor 16, a printed circuit board(PCB) 18, a superheat processor 20, a data-reporting or communicationmodule 22, and an Input/Output (IO) module 24. It will be understoodthat in lieu of the PCB 18, alternative substrates may be used formounting electronic components. For example, electronic components,including but not limited to those disclosed below, may be mounted on asubstrate formed from a polymer, ceramic, metal, or other desiredmaterial.

The housing 12 is the enclosure for all or a portion of the componentsof the universal superheat sensor 10. The illustrated housing 12 isprovides a hermetic or airtight sealed space within which themeasurement of the fluid may occur. The illustrated housing 12 includesa body 26 having an opening 28 in which the fluid inlet member 14 ismounted, and a cover 30 having an opening 32 in which the IO module 24is mounted. If desired, a seal (not shown) may be disposed between thebody 26 and the cover 30.

The body 26 and the cover 30 of the housing 12 may have any otherdesired size and shape, and may be formed from any desired material,such as plastic, metal, or ceramic. Alternatively, the fluid inletmember 14 may be formed from any other desired material.

In the embodiment illustrated in FIG. 2, the fluid inlet member 14 is abrass core or fitting having a centrally formed fluid passageway 34. Thefluid inlet member 14 connects the integrated pressure and temperaturesensor 16 to the source of superheat fluid (not shown). The fluid inletmember 14 may be any type of fitting, such as a standard ¼ inchSchrader® port. Any other desired type of fluid inlet member may also beused. Additionally, external adapters (not shown) may be attached to thefluid inlet member 14 to connect it to a variety of fluid fittings (notshown) of fluid systems, such as HVAC systems.

The illustrated integrated pressure and temperature sensor 16 is mountedto the PCB 18 and includes a wide-range pressure sensor portion 36 thatconverts fluid pressure to an electrical signal. The generatedelectrical signal may be subsequently used by the superheat processor20. As used in the description of the invention and the appended claims,the phrase “wide-range pressure sensor” is defined as a pressure sensorthat it will support common ranges of system pressures that occur inknown refrigerant systems while maintaining accuracy. The pressuresensor portion 36 may be any type of pressure sensor; including silicon,piezo-ceramic, capacitive, and integrated hall-effect transducers, andany other device that produces an electrical analogue of pressure. Inthe illustrated embodiment, the pressure sensor portion 36 of theintegrated pressure and temperature sensor 16 is a silicon transducer.As shown in FIG. 2, the integrated pressure and temperature sensor 16 isexposed directly to the pressurized superheat fluid via the fluid inletmember 14 for fast and accurate measurement.

The illustrated integrated pressure and temperature sensor 16 includes atemperature sensor portion 38 that converts temperature to an electricalsignal. The generated electrical signal may be subsequently used by thesuperheat processor 20. The illustrated temperature sensor portion 38 isprovided to measure the internal liquid refrigerant temperature, and isstructured and configured to support a wide range of fluid systemtemperatures, such as temperatures within the range of from about −50degrees C. to about +125 degrees C., while maintaining an acceptableaccuracy for a specific application. In some applications, an acceptableaccuracy may be +/−0.5 degrees C. In other applications, an acceptableaccuracy may be a range smaller or larger than +/−0.5 degrees C.Alternatively, the temperature sensor portion 38 may support fluidsystem temperatures within the range of from about −25 degrees C. toabout +150 degrees C. The temperature sensor portion 38 may be any typeof temperature sensor, including a thermistor, a thermocouple, aresistive element etched onto a substrate, a diode, or any other devicethat produces an electrical analogue of temperature. Advantageously, theillustrated integrated pressure and temperature sensor 16 is relativelysmall and physically close to the fluid to maximize both response timeand measurement accuracy. It will be understood that the temperaturesensor and the pressure sensor may be separate sensors as describedbelow.

The illustrated superheat processor 20 is mounted to the PCB 18 and is ahigh-resolution, high accuracy device that processes the input signalsfrom the pressure and temperature sensor portions 36 and 38,respectively, of the integrated pressure and temperature sensor 16,detects the fluid type, calculates the superheat of the fluid, andprovides an output that identifies the level of the calculatedsuperheat. The superheat processor 20 may also be configured to provideother data, such as fluid temperature, fluid pressure, fluid type,historical date maintained in an onboard memory (such as alarm andon-off history), and other desired information. The superheat processor20 may be configured as a high-resolution processor that is able detectand process, with a single pressure sensor and a single temperaturesensor, or with the illustrated integrated pressure and temperaturesensor 16, the wide-range of system pressures and temperatures that maybe encountered in the fluids of the fluid systems with which theuniversal superheat sensor 10 will be used, for example refrigerants ofHVAC systems. Advantageously, the superheat processor 20 maintains ahigh level of accuracy through one-time calibration over the operatingrange of pressure and temperature input. Non-limiting examples ofsuitable superheat processors include microcontrollers, FieldProgrammable Arrays (FPGA), and Application Specific Integrated Circuits(ASIC) with embedded and/or off-board memory and peripherals.

The illustrated communication module 22 is mounted to the PCB 18 and isa configurable hardware module that provides industry-standard Modbusdata over a hard-wired backbone, such as an RS485 hard-wired backbone,schematically illustrated at 40 in FIG. 2. If desired, the communicationmodule 22 may provide Modbus data and other communication protocols overcommunications means, such as RS232, I2C, SPI, and 4-20 mA, CurrentLoop, USB 2.0, Bluetooth, an RF module, and wireless information to acell-phone application. An internal antenna (not shown) may be providedto support the RF module. The illustrated communication module 22 isflexible enough to support other current and future communicationprotocols as they become available.

The illustrated IO module 24 is a physical hardware interface thataccepts input power and reports data through the available hard-wiredinterfaces. Common target devices that may be connected to the universalsuperheat sensor 10 via the IO module 24 are schematically illustratedat 42 in FIG. 2, and include, but are not limited to: additionaltemperature sensors (such as the temperature sensor 44 illustrated inFIG. 3) industry standard controller modules, laptop and notebookcomputers, cell phones, and memory cards such as non-volatile memorycards.

As shown in FIG. 3, an external temperature sensor 44 may be connectedto the IO module 24 via the backbone 40. Also, the external temperaturesensor 44 may be positioned near various components of a refrigerationsystem, such as an evaporator outlet and a compressor to measure theevaporator core temperature, the discharge temperature, and the like. Itwill be understood that any desired number of external temperaturesensors 44 may be connected to the IO module 24 to simultaneouslymeasure the temperature internally and at multiple components ordevices.

Advantageously, the superheat processor 20 may process the pressure andtemperature inputs from the integrated pressure and temperature sensor16 and the external temperature sensors 44, if provided. The superheatprocessor 20 is calibrated to detect and identify a plurality of fluidtypes. The superheat processor 20 further calculates the superheat ofany of the plurality of fluid types with a high degree of resolution andaccuracy. The superheat processor 20 may also determine error conditionsand store superheat and related parametric and alarm data. The superheatprocessor 20 may then report the superheat of the fluid system to whichthe superheat sensor 10 is attached. The superheat processor 20 may alsoreport additional data such as temperature, pressure, fluid type,on-time, alarms, operational history, and the like. Advantageously, thesuperheat processor 20 needs to be calibrated only one time, and maythereafter calculate superheat and perform any of the tasks describedabove for any of a plurality of fluid types.

Additionally, the embodiments of the universal superheat sensor 10, 60,70, and 80 described herein allow real-time data to be presented to auser, such as a contractor.

Referring again to FIG. 3, a second embodiment of the universalsuperheat sensor is shown at 60. The illustrated universal superheatsensor 60 includes the housing 12, the fluid inlet member 14, the PCB18, the superheat processor (not shown in FIG. 3), the communicationmodule (not shown in FIG. 3), the IO module 24, an internal pressuresensor 62, and an external temperature sensor 44, as described above. Asdescribed above, any desired number of external temperature sensors 44may be connected to the IO module 24 to simultaneously measure thetemperature at multiple components or devices.

Referring now to FIG. 4, a third embodiment of the universal superheatsensor is shown at 70. The illustrated universal superheat sensor 70includes the housing 12, the fluid inlet member 14, the PCB 18, thesuperheat processor (not shown in FIG. 4), the communication module (notshown in FIG. 4), the IO module 24, an internal pressure sensor 62, andan internal temperature sensor 72. It will be understood the any desirednumber of external temperature sensors 44 may also be connected to theIO module 24 to simultaneously measure the temperature internally and atmultiple components or devices. In addition to one or more externaltemperature sensors 44, if desired, the universal superheat sensor 80may also include one or more of the target devices 42 that may beconnected to the IO module 24 of the universal superheat sensor 80 viathe backbone 40, as described above.

Referring now to FIG. 5, a fourth embodiment of the universal superheatsensor is shown at 80. The illustrated universal superheat sensor 80includes a housing 82, a fluid inlet member 84, the PCB 88, thesuperheat processor 90, the communication module 92, and the IO module94. The universal superheat sensor 80 may include the integratedpressure and temperature sensor 16. Alternatively, the universalsuperheat sensor 80 may include an internal temperature sensor and aninternal pressure sensor, neither of which are shown in FIG. 5, but bothof which are described above. The illustrated housing 82 includes a body100 having an opening (not shown) in which the fluid inlet member 84 ismounted, and a cover 102. A seal 104 may be disposed between the body100 and the cover 102. If desired, the universal superheat sensor 70 mayalso include one or more external temperature sensors 44, as describedabove, and may further include one or more target devices 42 that may beconnected to the IO module 24 of the universal superheat sensor 70 viathe backbone 40, as described above.

The principle and mode of operation of the universal superheat sensorhave been described in its preferred embodiments. However, it should benoted that the universal superheat sensor described herein may bepracticed otherwise than as specifically illustrated and describedwithout departing from its scope.

What is claimed is:
 1. A superheat sensor comprising: a housing; apressure sensor mounted within the housing; a fluid passagewayconnecting the pressure sensor to a source of superheat fluid; and aprocessor.
 2. The superheat sensor according to claim 1, furtherincluding a fluid inlet member having the fluid passageway formedtherethrough, the fluid inlet member selectively connectable to aplurality of fluid systems.
 3. The superheat sensor according to claim1, wherein the pressure sensor produces an electrical analogue ofpressure.
 4. The superheat sensor according to claim 3, wherein thepressure sensor is one of a silicon, piezo-ceramic, capacitive, andintegrated hall-effect transducer.
 5. The superheat sensor according toclaim 2, further including a temperature sensor mounted within thehousing.
 6. The superheat sensor according to claim 5, further includinga communication module configured to transmit data to a target device.7. The superheat sensor according to claim 5, wherein the temperaturesensor produces an electrical analogue of temperature.
 8. The superheatsensor according to claim 7, wherein the temperature sensor is one of athermistor, a thermocouple, a resistive element etched onto a substrate,and a diode.
 9. The superheat sensor according to claim 2, furtherincluding an external temperature sensor electrically connected to theprocessor.
 10. The superheat sensor according to claim 9, furtherincluding a temperature sensor mounted within the housing.
 11. Thesuperheat sensor according to claim 9, wherein the external temperaturesensor is configured for attachment to a heat generating component of afluid system.
 12. The superheat sensor according to claim 1, wherein theprocessor is configured to process input signals from the pressuresensor and the temperature sensor, detect a fluid type, calculate asuperheat of the fluid, provide an output that identifies the level ofthe calculated superheat, provide fluid temperature, provide fluidpressure, provide fluid type, and provide historical date datamaintained in an onboard memory.
 13. The superheat sensor according toclaim 1, further including an Input/Output (IO) module configured toreport data to a target device through an interface.
 14. The superheatsensor according to claim 13, wherein the target device is one of atemperature sensor, a controller module, a computer, a cell phone, and amemory card.
 15. A method of sensing superheat comprising: connecting afluid inlet member of a superheat sensor to one of a plurality of fluidsystems; allowing fluid to flow from the fluid system to which thesuperheat sensor is connected to the superheat sensor; sensing atemperature of the fluid in the fluid system with one of an internaltemperature sensor mounted within a housing of the superheat sensor andan external temperature sensor mounted outside of the housing of thesuperheat sensor; and calculating a superheat of the fluid in the fluidsystem.
 16. The method of sensing superheat according to claim 15further comprising the step of sensing a pressure of the fluid in thefluid system with a pressure sensor mounted within a housing of thesuperheat sensor.
 17. The method of sensing superheat according to claim16 further comprising the step of calibrating the superheat sensor todetect and identify a plurality of fluid types.
 18. The method ofsensing superheat according to claim 17 further comprising the step ofcalculating the superheat of any of the plurality of fluid types.
 19. Amethod of sensing superheat comprising: calibrating a superheat sensor;connecting a fluid inlet member of the superheat sensor to one of aplurality of fluid systems; allowing fluid to flow from the fluid systemto which the superheat sensor is connected to the superheat sensor;sensing a temperature of the fluid in the fluid system; detecting afluid type of the fluid in the fluid system; calculating a superheat ofthe fluid in the fluid system; determining error conditions; storingsuperheat and related parametric and alarm data; disconnecting thesuperheat sensor and subsequently connecting the superheat sensor toanother of the plurality of fluid systems without re-calibrating thesuperheat sensor.
 20. The method of sensing superheat according to claim19 further comprising the step of reporting any of temperature data,pressure data, fluid type, on-time data, alarm data, and operationalhistory data.